Circulatory assist devices are needed for immediate temporary treatment of acute myocardial infarction and for some postcardiotomy patients. Implanted circulatory assist devices also are being developed for longer term help to ambulatory patients with chronic heart failure. Pneumatic and electromagnetically actuated pulsatile assist devices have been investigated, and in recent years there has been development of continuous flow rotary blood pumps, smaller and simpler than pulsatile devices, which do not require valves. Rotary pumps, however, need sliding bearings and seals or magnetic transmissions, which limit their usefulness. There is still a controversy, also, concerning the adequacy of continuous flow assistance, and whether there is a biological need for pulsatile blood flow. The proposed research program seeks to provide improved circulatory assist devices as well as extracorporeal blood pumps of both types based on a vibratory orbiting centrifugal pumping principle. A small implantable VAD will be designed with potential for optional continuous or pulsatile pumping. The VAD will have no valves, rotating bearings, or seals. An analytical and experimental program to provide a design for an optimized vibratory orbiting blood pump is presented. A substantial market is anticipated.